Vaccination (protective inoculation) is a process by which specific antibodies are either developed or infected to a normal man to immune the body from specific disease caused due to pathogens.
The process of introduction of vaccine into an individual to provide protection against a particular disease is called vaccination.
These vaccines (inactivated or weakened pathogen) generate primary immune response (i.e. memory B & T cells) which attack the pathogens.
Edward Jenner the “Father of Immunology” (1749-1823), conceived the idea of vaccination when he observed that the milkmaids did not suffer from small pox, a dreaded disease, as they were exposed to a milder form of this disease called cowpox. So he proposed that an induced mild form of a disease would protect a person from a virulent form (which can cause more damage to the host).
He termed it as vaccine (Latin-Vacca means “Cow”) and vaccination for protective inoculation. Jenner, the county doctor, experimented this concept successfully on a healthy body named James Philips in 1796 and could save thousands of people from his discovery. Nearly after a century, Lewis Pasteur (1881) succeeded in producing vaccines for anthrax, rabies (hydrophobia). Victims of bites by rabid dogs are now immunized by a series of injections called pasteur treatment.
Types of Vaccines:
1. Attenuated whole-agent vaccine:
It is the use of living attenuated (weakened) microbes. Example- Sabin polio vaccine, vaccine for measles, mumps and rubbella (MMR) and typhoid vaccines etc.)
These are inactivated toxins which act as vaccines against diseases like tetanus and diphtheria.
3. Inactivated whole-agent vaccines:
Inactivated vaccines (microbes killed by formalin or phenol) are used against diseases like cholera, rabies, pneumonia etc.
4. Subunit Vaccines (Recombinant vaccines):
These are antigenic fragments of microbes that stimulate immune response. (Ex-Hepatitis B).
5. Nucleic acid Vaccines:
DNA and RNAs are now in experimental stage of vaccines.
6. Conjugated vaccines:
These are polysaccharides combined with proteins. It is recent and effective against Haemophilus fluenzae (type b).
Still researches are going to develop effective vaccines against Malaria, Leprosy, AIDS, Dental carries etc.
Vaccine development by Recombinant DNA Technique:
The rDNA or Recombinant DNA technology has been used for safe and high productivity vaccines. In this method, the gene for the active immunogen is separated for the pathogen and is introduced into a more convenient and benign system for high production and safe vaccine i.e. without side effects. A number of vaccine target are currently under investigation, such as (i) Hepatitis B, Herpes, Malaria, Pertussis, Dental carries, Rabies, Cholera and Aids.
The Hepatitis B vaccine may also prove to be an anti-tumour vaccine as hepatitis B infection is closely linked with hepatocarcinoma. The human papilloma virus vaccine could be effective against cancer of cervix and vulva. Efforts are on to design specific tumour antigen based vaccines.
Immunization is the process by which the body produces antibodies against the vaccine preventable diseases through admistration of specific vaccines. Vaccination provides immunisation after a time period. So passive immunisation is practised in such cases where prepared antibodies, antitoxins and antivenoms are injected to the patients. Ex. Tetanus, Snake bite.
Recently gene controlling the formation of immunogenic proteins is isolated from DNA. It is cloned and integrated with a vector for introduction into an individual to be immunized. Immunisation of pregnant women is restricted.